Client wanted to move ViewState off the page to reduce page weight. Hadn't done this for awhile (read ages) so I found this article and the discussion about where to move it to. So I went with cache and allow them to change it or turn it off completely.
It did help the page weight..decreased it by almost a third. I will do some timing tests to see what difference it has made. We're keeping 2 pages of data and monitoring to see if we need more.
So then I moved some of the javascript sitting on the aspx pages into extenal files and reduced it by half! Now to look into moving all the javascript in the code behind into files aswell.